Further Experiments on Transition to Turbulence in Constant-Acceleration Pipe Flow

A second series of experiments was conducted to extend and validate recently reported data by the present authors on transition to turbulence in pipe flows started from rest under constant acceleration. The test section diameter was increased from the 5 cm of the previous experiment to 9 cm for the present study. The low end of the acceleration range was also extended by an order of magnitude from 1.8 m/s² down to 0.2 m/s². The highest acceleration was 11.2 m/s². Pipe Reynolds number at transition was observed to be as high as 1.1 × 10⁶. The present results are shown to validate the previously suggested transition correlation parameters. An analysis based on an empirical equation for transition in convectively accelerated flows is extended and applied to the current experimental data.